The overall objectives of the research proposed in this project are to determine the phenotypic properties and in vitro and in vivo sensitivity of clonal subpopulations obtained from heterogeneous human brain tumors to selected therapies, including chemotherapeutic agents, growth factors, antiangiogenesis compounds, and ionizing radiation (see also Projects 2- 4). These studies will provide insight into the rational approach to selection of specific regimens for the treatment of individual patients and therefore, provide novel and effective therapeutic benefits. The specific aims of this project include the isolation of tumor lines from human brain tumors and the subcloning of this material to provide subpopulations with varying responses to drugs such as 5-fluoruracil, cis-platinum, AZT, ido- and bromodeoxyuridine. We also propose to use differentiation-inducing agents such as N-methylformamide (NMF) in combined modality studies (e.g., x-rays plus NMF plus iododeoxyuridine), as this agent has been shown to alter the phenotype of cancer cells so that they become more radiosensitive. We will investigate the use of WR- 2721 as a radioprotective agent for normal brain. Although this agent does not cross the blood-brain-barrier normally, it will penetrate normal brain tissue in the region of brain tumors and is therefore, an excellent agent for radioprotective purposes in the radiosurgery situation. Both single agent and combination agent cytotoxicities will be investigated, both in vitro and in vivo. Additionally, tumor lines will be assayed using molecular biological and biochemical techniques to determine the levels of expression and protein for important mitogenic and angiogenic growth factors such as transforming growth factors -a and -B and members of the fibroblast growth factor. These studies interrelate with the antiangiogenesis work in Project 2. Additionally, we propose to incorporate interesting agents into pellets (project 4) which can be implanted into brain tumors to provide both chemosensitization (project 1) and radiosensitization (project 3). Brain tumor lines will be characterized radiobiologically to provide information on tumor cell survival at high radiation doses used in radiosurgery. We will also assay the fractions of hypoxic cells in xenografted solid brain tumors transplanted in nude mice in vivo. Hypoxic fractions in xenografted brain tumors will be correlated with expression of angiogenic growth factors by individual tumor lines. The first year of this work will be concerned primarily with in vitro studies. Combined modality and in vivo work will begin as soon as feasible, i.e. by the beginning of year 2. Interaction with project 3 and 4 will begin in year 3. These novel chemotherapeutic, molecular, and radiobiological protocols should provide new experimental insights into optimal treatment of heterogeneous human brain tumors.